CA3003368C - Method for manufacturing a blade preform, a blade and a nozzle segment by selective powder-bed fusion - Google Patents

Abstract

The invention relates to a method for making a turbomachine wave preform by selective powder bed fusion. The turbomachine comprises a wave and at least one removable medium attached to the wave, the wave being made layer by layer from a first wave edge corresponding to a leading edge or a trailing edge of the wave up to a second wave edge corresponding to a trailing edge or a leading edge of the wave, the method comprising the making of the removable medium and of the wave, said removable medium being intended to be attached to a build platform on the one hand, and to a portion of the face of the wave located near the first wave edge with respect to said build platform on the other hand. The face of the wave with respect to the build platform comprises a plane extending from said face, the plane being present on a portion of said face located outside the first wave edge, the medium being attached to the plane or simultaneously to the plane and a portion of said face outside the first edge. The invention also relates to a method for making a wave and a distribution sector for a turbomachine, as well as a wave preform.

Description

Method for manufacturing a blade preform, a blade and a distributor sector by selective powder bed fusion Background of the invention The present invention relates to the general field of additive manufacturing processes. The present invention relates more particularly a method of manufacturing blades for a turbomachine by selective melting on a powder bed.
Today it is common and advantageous to have recourse to additive manufacturing techniques to easily and quickly produce complex three-dimensional parts. The aeronautical field lends itself particularly well to the use of this type of process.
When it comes to the manufacture of metal or alloy parts metal, the selective melting process on a powder bed allows to obtain complex parts which are difficult to produce or not achievable with conventional processes such as foundry, forging or machining.
Such a method typically includes a step during which a layer of powder is deposited on a manufacturing plate, then a step of selective melting of part of the layer of powder deposited using a heating device. The previous steps are successively repeated to form, layer after layer, the part final.
Figure 1 shows a turbine nozzle sector 1 for aeronautical turbomachine comprising a plurality of vanes 2 fixed extending between two concentric rings 3 and 4, arranged on a build plate 5 horizontal. When the distributor is in a such configuration, the blades 2 are suspended or cantilevered compared to rings 3 and 4.
When one wishes to manufacture such a distributor sector 1 by selective melting on a powder bed, it is necessary to provide during there manufacture of removable or breakable supports 6 (see FIG. 1) which maintain the blades during their manufacture. Indeed, in the selective powder bed fusion processes, it is mandatory that each merged layer can be supported by material already previously merged. Such supports 6 are inevitably present

2 at the level of the leading edge or the trailing edge (depending on whether the sector of distributor is made in one direction or the other) of the blades 2, and on a part of the face 2a of the blades facing the production plate 5 (see figure 5).
However, the presence of these removable media at the level of the leading edge or trailing edge is not desirable. Indeed, once the distributor sector manufactured in selective melting tooling on bed of powder, and separated from its manufacturing plate, the removable supports must be removed. A manual polishing step is necessary to remove residues from these supports. During the manual polishing step, the operator is required to move the polishing tool over the edge on which the supports are present (corresponding to the leading or trailing edge dawn) and lean on it. Manual polishing can thus cause defects in shape and irregularities on the edge concerned due to excessive material removal. Such defects can prove to be problematic for the aerodynamics of the blades during their subsequent use in a turbomachine.
Subject matter and summary of the invention The main purpose of the present invention is therefore to overcome such disadvantages in proposing a manufacturing process by selective melting on a powder bed of a blade preform for a turbomachine comprising a vane and at least one removable support fixed to the vane, the vane being manufactured layer by layer from a first edge of the blade corresponding to a leading edge or a trailing edge from the blade to a second edge of the blade corresponding to a trailing edge or to a leading edge of the blade, the method comprising fabricating the support removable and of the blade, said removable support being intended to be fixed on a production plate on the one hand, and on a portion of a face forming intrados or extrados of the blade located in the vicinity of the first edge of the dawn facing said production plate on the other hand.
In accordance with the invention, the face forming the intrados or extrados of the blade opposite the manufacturing plate comprises a flat extending from said face, the flat being present on a portion of said face situated outside the first edge of the blade, the WO 2017/08538

3 removable support being fixed on the flat or both on the flat and on a portion of said face located outside the first edge.
The process according to the invention is remarkable for the integration during manufacture of the blade preform of a flat at the level of the first edge of the blade (the first edge possibly corresponding to an edge leading or trailing edge depending on the orientation of the blade in the tooling selective melting on a powder bed). The presence of this flat allows advantageously to distance the portion of the blade on which the support removable is attached to the first edge considered. In other words, the removable support is positioned set back relative to the first edge of dawn. When the removable media is subsequently removed to obtain at dawn, the support residues are localized on the flat and possibly on part of the face of the blade facing the plate workmanship, but not directly on the first edge. Thus, during the blade polishing to remove these residues, the operator can lean on more on the first edge of the blade, but on the flat and the face of the blade near which the flat is present. Such a provision therefore makes it possible to limit the appearance of defects due to the removal of the supports ensuring uniform and controlled polishing of the blade. Furthermore, the blade adjustment or polishing time is reduced by such technique, making this step more systematic. Of course, techniques other than polishing can be used to adjust the shape of the blade after removal of supports.
Preferably, the flat comprises a first face parallel to the build plate and tangent to the first edge of the blade. By example, the first face can form an angle less than or equal to 50 with the build plate. As the part is made layer by layer, each layer being parallel to the build plate, this means that the first layer forming the blade will be a surface, for rectangular example. It is advantageous for the first layer to be a surface rather than a line, to ensure better support and the blade, in particular at the level of its first edge.
Also preferably, the flat further comprises a second face perpendicular to the first face. For example, the second face can form an angle between 85 and 950 with the first side. In this case, a point on the flat at the intersection of the

4 first and second faces of said flat may be located at a distance of the face of the blade opposite the manufacturing plate less than or equal to 0.5 mm, for example less than or equal to 0.3 mm. way more general, the flat can be integrated into the vane so that it does not protrude not the admissible shape defect of the blade (dictated by a specification charges for example) or, in other words, to fit within the blade shape requirements. Thus, when the flat is constructed from the so, its dimensions are less than the defect in shape admissible for dawn, and its subsequent removal, for example by machining, can become optional.
The removable support can be a honeycomb support.
The invention also relates to a method of manufacturing a blade for a turbomachine, comprising the following steps:
- the manufacture of a blade preform by a process such as the one presented above, and - removal of the removable support and the flat part of the preform of dawn.
Preferably, the removal of the removable support and the flat includes vane polishing.
The invention also relates to a method for manufacturing a sector turbomachine distributor by selective melting on a powder bed, the nozzle sector comprising a plurality of stationary vanes carried by two ring sectors, the stationary vanes being manufactured by a process manufacturing a blade such as that described above.
The invention finally relates to a turbine engine blade preform comprising a blade and at least one removable support fixed to the blade, one of the faces of the blade forming the intrados or extrados comprising a flat extending from said face, the flat being present on a portion of said face situated outside a first edge of the blade corresponding to a leading edge or a trailing edge of the blade, the removable support being fixed on the flat or both on the flat and on a portion of said face located outside the first edge.
Preferably, the flat comprises a first tangent face at the first edge of the dawn and a second face substantially perpendicular to the first face.

Brief description of the drawings Other Features and Advantages of the Present Invention will emerge from the description given below, with reference to the drawings annexed. In the figures:

5 - figure 1 is a perspective view of a sector of distributor which can be manufactured by a method according to the invention, - Figure 2 is a flowchart representing the main steps of a method for manufacturing a blade according to the invention, - Figure 3 is a schematic sectional view of a tool for selective melting on a powder bed in which a sector of distributer, - Figure 4 is a detailed view of Figure 3 at the level of the first edge of a blade and its removable support, and - Figure 5 is a view similar to that of Figure 3 illustrating a method of the prior art.
Detailed description of the invention Figure 1 shows a distributor sector 1 or rectifier of turbine for an aeronautical turbomachine, which has already been briefly described.
Such a distributor sector 1 can be manufactured by a process according to the invention by selective melting on a powder bed. A step in the process of fabrication involves the fabrication of 2 blades of the nozzle sector 1. It will be noted that the invention applies equally to blades for land or aeronautical turbomachines.
A method of manufacturing a blade 2 according to the invention will now be described with reference to the flowchart of Figure 2 and to the selective melting tooling shown in Figures 3 and 4. Such process first includes the manufacture of a blade preform (step El), then the removal (step E2) of the removable support 6 from the preform to obtain dawn. The support 6 is thus said to be removable because it is intended to be removed from the blade 2 after its manufacture by a method according to the invention.
FIG. 3 shows a tool 10 for selective melting on a bed of powder that can be used to craft a Dispenser Sector 1 provided with a plurality of fixed blades 2. For reasons of simplification, one has shown the tooling 10 in section during the manufacture of a sector distributor 1 comprising only two blades 2.

6 In a manner known per se, the tool 10 comprises a reservoir of powder 12 and a manufacturing zone 14 in which the dispenser area 1. Powder tank 12 contains powder 16 metal or a metal alloy which will be used to manufacture the sector of distributor 1, while zone 14 is able to contain the sector of dispenser 1 once made as well as unfused powder 18.
At the bottom of the powder tank 12 there is a tray 20 suitable to move vertically to bring powder in front of a scraper or roller 22 which can then push the powder towards the zone of manufacturing 14 so as to form a layer of powder. At the bottom of the manufacturing area 14 there is a manufacturing plate 5 capable of being move vertically as the sector is made dispenser 1. The scraper or roller 22, constituting a spreading means of powder, makes it possible to deposit a layer of powder on the plate of manufacturing 5.
The tool 10 finally comprises a heating member 23 provided of a generating portion 24 of a laser beam or of a beam of electrons and a portion 25 making it possible to control the trajectory of the generated beam to selectively fuse a layer of powder deposited in the manufacturing zone 14.
For each blade 2, provision is made for the manufacture of a support removable 6 fixed on the manufacturing plate 5 on the one hand, and on the blade 2 on the other hand, which makes it possible to maintain the blade 2 throughout the process of manufacturing. We are thus going to manufacture a blade preform which comprises a blade 2 and its removable support 6.
Figure 4 shows an enlarged schematic view of a blade preform in the manufacturing zone 14 at the level of the support removable 6. The blade preform is here made in the direction shown by arrow 26. The manufacture of the blade preform begins with the support 6, then blade 2 is made starting from a first edge 28 (corresponding here to the trailing edge of the dawn) and up to a second edge (corresponding here to the leading edge of the dawn, not represented). Thus, as can be seen in the figures, the first edge 28 is located opposite the manufacturing plate 5, while the second edge is located opposite said manufacturing plate 5. In addition, the

7 first 28 and second edges are generally parallel to the surface top of the build plate.
In accordance with the invention, a flat 30 is provided on dawn 2, more precisely on a face 2a of the dawn, and at the level of the first edge 28 of dawn. This flat 30 extends from a vicinity of the first edge 28 and in the opposite direction to the first edge 28, on the side of the face 2a of the blade opposite the manufacturing plate 5 (this face corresponds here to the extrados of the dawn). In the example shown the flat 30 comprises a first face 30a substantially parallel to the plate of fabrication 5 and tangent to the first edge 28 of the blade, and a second face 30b substantially perpendicular to the first face 30a. In this configuration, a point 30c located at the intersection of the two faces is at a distance cl from the face 2a of the blade. Preferably, this distance d is less than or equal to 0.5 mm, or even less than or equal to 0.3 mm, for respect the admissible form defect for blade 2. In such a way general, the distance d can be chosen less than or equal to the value of the form defect admissible for blade 2, the form defect being generally defined by specifications.
The removable support 6 here comprises a plurality of low walls 6a (or legs) which are intended to support dawn 2. These low walls 6a are fixed on a portion of the blade 2 extending from the flat 30 to the face 2a of the dawn and in a direction opposite to the first edge 28. The low walls 6a can be fixed on the flat and set back from the first edge 28 of dawn, that is to say that the low walls 6a are not positioned at level with the first edge of the blade and are far from it. In a embodiment not shown, the low walls 6a can be fixed on a portion extending from the middle of the face 30a of the flat 30, and up to on face 2a of the dawn.
It will be noted that the support 6, the flat 30 and the blade 2 do not form one and the same part (referred to here as the blade preform) to the end of stage El.
The removable support 6 is preferably of the honeycomb type. Of generally, the removable medium 6 may not be full, and therefore example be hollow. Thus, we avoid consuming too much material during the manufacturing process, as the support 6 will eventually be removed of the dawn preform.

8 The dotted line 32 in Figure 4 represents the first layer that constitutes the blade, we see that the fused part of this first layer which begins the manufacture of blade 2 forms a plane thanks to to the presence of the flat 30. Obtaining a first blade layer constituted by a plan is advantageous. Indeed, in additive manufacturing, we avoid as much as possible to start a piece by merging a simple line to minimize manufacturing defects. Moreover, in starting the manufacture of dawn 2 with a plan, it will be better maintained by bracket 6.
Once the blade preform has been manufactured (or the plurality blade preforms of a distributor or a straightener), the support removable 6 can be removed by cutting at the low walls 6a (step E2). The residues of walls 6a of the remaining support 6 and the flat 30 are then removed, for example with a polishing tool of the type grinder. The presence of the flat 30 makes it possible not to press the cutting tool polishing on the first edge 28 during this step. In fact, we can rather position the polishing tool on the flat 30 and at the level of the face 2a, so as not to damage the first edge 28. In addition, it turns out more easy to take support with the polishing tool on the face 2a, rather than on the first edge 28. The presence of the flat therefore makes it possible to obtain blades whose first edges 28 are regular and do not have any defects beyond the admissible defect defined by a specification.
It will be noted that the scope of the invention is not departed from when several supports 6 are used to support a blade 2.
For comparison, the positioning of a removable medium 6 as it can be realized in the prior art is illustrated in FIG.
5.
In this configuration at least one low wall 6a of support 6 is positioned on the first edge 28 to be able to hold the vane properly during manufacture. Also, the first layer forming the blade 2 (shown by the dotted line 32) consists by a line, which is not desirable for the reasons mentioned previously. After removal by section of the support 6, at least one wall residue 6a will inevitably be positioned on the first edge 28.
The presence of this residue will make the adjustment stages more difficult and of blade polishing, and may cause defects in this edge and an irregularity on all of the blades 2 manufactured.

Claims (10)

9 1. Manufacturing process by selective melting on a powder bed of a blade preform for a turbomachine comprising a blade and at least at least one removable support fixed to the blade, the blade being made layer per layer from a first edge of the blade corresponding to an edge leading or at a trailing edge of the blade to a second edge of the blade corresponding to a trailing edge or to a leading edge of the blade, the method comprising the manufacture of the removable support and the blade, said removable support being intended to be fixed on a tray of manufacture on the one hand, and on a portion of a face forming an intrados or extrados of the blade located in the vicinity of the first edge of the blade in facing said manufacturing platform on the other hand, characterized in that the face forming the intrados or extrados of the blade facing the build plate has a flat extending from said face, the flat being present on a portion of said face situated outside the first edge of the blade, the removable support being fixed on the flat or both on the flat and on a portion of said face located outside the first edge. 2. Method according to claim 1, characterized in that the flat includes a first face parallel to the build plate and tangent to the first edge of dawn. 3. Method according to claim 2, characterized in that the flat further comprises a second face perpendicular to the first side. 4. Method according to claim 3, characterized in that a point of the flat at the intersection of the first and second faces of said flat is located at a distance (d) from the face of the blade facing the build plate less than or equal to 0.5 mm. 5. Method according to any one of claims 1 to 4, characterized in that the removable support is a honeycomb support. 6. Process for manufacturing a blade for a turbomachine, characterized in that it comprises the following steps:
- the manufacture of a blade preform (step E1) by a method according to any one of claims 1 to 5, and - removal (step E2) of the removable support and the flat part of the dawn preform. 7. Method according to claim 6, characterized in that the removal of the removable support and the flat includes polishing the blade. 8. Method of manufacturing a key sector distributor of turbomachine by selective fusion on a powder bed, the sector of distributor comprising a plurality of fixed blades carried by two ring sectors, characterized in that the stationary vanes are made by a method of manufacturing a blade according to any one of claims 6 and 7. 9. Turbomachine blade preform comprising a blade and at least one removable support fixed to the blade, characterized in that a of the faces of the blade forming the intrados or the extrados comprises a flat extending from said face, the flat being present on a portion of said face situated outside a corresponding first edge of the blade at a leading edge or at a trailing edge of the blade, the removable support being fixed on the flat or both on the flat and on a portion of said face located outside the first edge. 10. Preform according to claim 9, characterized in that the flat includes a first face tangent to the first edge of the blade and a second face forming an angle between 85 and 950 with the first side.